Mecury-vapor lamp.



` H. N. POTTER.v MEHBURY VAPOR LAMP (No Model.)

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UNITED STATES PATENT OFFICE.

HENRY NOEL POTTER, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO GEORGE VESYIINGHOUSE, .OF PITTSBURGfPENNSYLVANIA.

M ERouRY-VAPOR LAM P.

SPECIFICATION forming part of Letters Patent N o. 707,976, dated August 26, 1902.

Original application led July 24, 1900, Serial No. 24,651. Divided and this application iiled December 3l, 1900. Serial No.41,595. (Nomodcl.)

T0 all whom, twenty concern:

Beit known that I, HENRY NOEL POTTER, a citizen of the United States, and a resident of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Mercury- Vapor Lamps,of which the followingis a speciflcation.

My invention relates to `improvements in gas or vapor lamps, the details of which improvements will be fully*V described in the specification which follows and more particularly pointed out in theclaims. As an example of lamps of this class I select for illustration and description in the present instance a lamp containing mercury-vapor. Experience has shown that the efficiency of lamps of this type depends largely on the ratio of the cross-sectional area of the path of the electric current or stream to the surface of the tube in which the mercury-vapor is hermetically inclosed. -In general it appears to be a fact that a small tube having a proportionately-large surface and small area of crosssection gives the highest efficiency. By reason of the peculiar property of gases, which makes them absorb light of such Wave lengths as they can themselves emit when luminous, the portions of gas or vapor lying near the surface of the luminous stream in a mercuryvapor lamp are somewhat opaque to the lightrays given off by the more central portions of the gas. Moreover, the vapor of mercury has a temperature of maximum efficiency beyond which it is easily possible to heat it. Both v these peculiarities conspire to render it advantageous to increase the radiating-surface and decrease the cross-section of the luminous stream. The means which I have provided for securing the result named consist in employingfor .the inclosing gas or vapor chamber tubes which have a portion of their bore (the central portion) occupied by a non-conducting material, andthe irst part of my invention is concerned with the utilization' of such a tube for the purposes indicated.

To counteract the tendency of mercuryvapor to become heated by the electric cur-l rent to a temperature too high for maximum efii'ciency, it has been suggested that the vapor be artificially cooled-sayv by inner chimneys or liquid-cooling tubes within the lighting-chamber; but it is plain-ly advisable if possible to so design the tube or lightingchamber that only enoughheat is generated to bring the vapor to its temperature of vmaximum eciency and to so dispose'this vapor in space as to'permit the greatest possible portion of the light to be freely emitted. To this end I propose to provide the luminous chamber of my lamp with a vacuum-jacket whereby, for a given expenditure of energy, the temperature ofthe chamber, or rather of the tube forming the chamber, will be higher than it would be if the surface of the tube were permitted, as at present, to dissipate heat by radiation,conduction,and convection.

The other details of my lamp construction, together with the 'arrangementof the lamp in an electric circuit, will be fully. set forthl hereinafter and will be clearly understood by reference to the accompanying drawing, which is a vertical section of my lamp, combined with a diagram of the electric circuits.

In the drawing,- 1 is an inner tube or rod of suitable material, arranged centrally within a second tube 3, of transparent material, such as glass, so as Vto leave an annular space 2.

Upon the tube 3 is'mounted a coil or spiral of wire 4, this wire being of nickel, German silver, or other suitable material. The tube 3, together with its heating-coil 4, is sealed into a glasstube 12, leaving a second annular space 1l. Leading-in wires. 5 andv 6' pass through the tube 12 and are connected to the opposite ends of the conductor 4. The tubes 1 and 3- are joined together or braced in position at their lower ends, and a small quantity of mercury 7 is introduced into the bottom of the tube 3. A branch 8 from the leading-in wire 5 runs to the mercury 7, thus connecting the latter with the outside surface. At the upperend-of the tube abulb 13 issealed on, having a narrow cylindrical portion 14 at its upper end. Within the bulb 13 and extending upward somewhat into the cyl-y inder 14 is an electrode 9, constituting the an- IOO The tube 1 may have a projecting lug or extension 34 to steady the anode, and it may itself be braced or supported by any suitable means within the tube 3. It will generally be best to employ glass braces located within the bulb 13 rather than within the lighting-chamberformedbytheannularspace2. The function of the bulb or enlarged chamber 13 is to constitute a cooling or condensing chamber, and the function of the projecting tube or cylinder 14 is to provide also for the collection of impurities, and so make the upper portion of the lamp perform the double service of cooling or condensing the vapors and purifying them through the deposition of the impurities contained therein. The walls of the cylinder 14 will be cool relatively to the walls of tne bulbous portion 13, the latter element being the one which discharges the greater portion of the condensing function. By reason of the position of the anode 9 at the mouth of the cylinder 14 the gases in the annular space at the mouth of the said cylinder are made hot, thereby facilitating the passage of impurities into the cylinder, while at the same time violent currents of gas surging into and out of the cylinder' (which might disturb the lodgmeut of gaseous impurities therein) are prevented. The annular space 11 is exhausted to a high vacuum to prevent as far as possible the transfer of heat from the heated surface of the tube 3 by conduction and convection. The operating electric current passes through the annular space 2, proceeding from the anode 9 to the cathode 7.

1f desired, the tube 1 may be exhausted of air to reduce the pressure on its walls due to the heated atmosphere inside the said tube when' the lamp is operated. It is not necessary, however, that this should be done.

The electrical connections of the lamp are illustrated diagrammaticallyin the drawing.

At 18 is shown a source of electrical energy having mains 16 and 17`proceeding therefrom. A wire 15 connects the main 16 with the common lamp and heater terminals 5 and 7. The opposite end of the heater is connected by the leading-in wire 6 with a wire 32, running to a suitable iuterrupter 31, which may be of the well-known \Venhelt or Simon type. Beyond the interrupter 31 the circuit proceeds by way of a wire 35 to the primary 29 of an ind uction-coil and through the said primary by means of a wire 36 to a switchpoint 28. By means of the switch-point 28 connection is established with a movable lever 20, which is pivoted at 37 and held by a spring 21 against the switch-point 28. The lever 2O is connected with the main 17 by means of a Wire 19, including a switch 38.

-The free end of the lever 20 is joined by a wire 39 to the secondary 30 of the inductioncoil above mentioned. The opposite end of the secondary 30 is joined by a wire 40 to a switch-point 27, located opposite the switchpoint 28 and so placed that the lever 2O may make contact with it when moved away from the last-named switch-point. The contact 27 is further connected with a ballast resistance 26, part or all of which is in the form of a solenoid 24 in inductive relation toacore 23. The last-named element is connected to the lever 2O and is adapted when suiiiciently attracted by the solenoid 24 to move the lever away from lodgment against the switch-point or contact 28 to lodgment against the switchpoint or contact 27. When the lever has been so moved, the secondary 30 of the induction-coil is short-circuited. The solenoid 24 is connected by a wire 41 through a resistance 52 to the leading-in wire 10, which extends to the anode 9 of the lamp. Theresistance 26, the solenoid 24, and the resistance 52 may all be regarded as a common ballast resistance for the lam p, and they may, in fact, be united in a single coil, constituting a magnet or solenoid for operating the lever 20.

The operation ofthe apparatus as a whole is as follows: On closing the switch 38 current passes from the main 17 through the wire 19, switch-lever 20, contact-point 28, wire 36, primary 29, wire 35, interrupter 31, wire 32, leading-in wire 6, heater-coil 4, leading-in Wire 5, and wire 15 to the main 16. The current thus turned on causes the heater-coil 4 to become warm, thus heating the tube 3 and the space and matter within it, including the mercury. At the same time the interrupter 31 is at work, causing pulsations in the primary of the induction-coil and an alternating electromotive force in the secondary thereof. As soon, now, as the mercury in the tube 3 has been warmed to a favorable starting temperature the secondary electromotive force causes a starting-current to flow in the lamp, after which the lamp-circuit is maintained in operation by the current from the mains. The current traversing the secondary of the induction-coil also traverses the coil 24 and is of suihcient quantity to cause the latter to attract its core 23, thereby moving the lever 20, breaking contact between the lever and the switch-point 28 and making contact between the lever and the switch-point 27. By the first action the heater, the primary of the induction-coil, and the interrupter are cut out, and by the second action the secondary of the induction-coil is short-circuited, thus protecting it from unnecessary and injurious heating due to the lam p-current. If for any reason the lamp should go out, the lever 20 returns to contact with the switch-point 28, thereby bringing the circuits into the proper condition for restarting the lamp. Instead of connecting up the heater in series with the primary of the induction-coil and the interrupter the heater may be connected in parallel circuit with the other elements named, as indicated in dotted lines at 42 and 43. In that case a portion of the wire 32 between the points 44 and 45 will be cut away and TOO IIO

the respective parallel circuits Will have to be so modified as to operate across the voltage of the entire line.

The claims of the present application re- 5 late to the lamp structure, the method vin- Volved in its operation being claimed in an application, serially nu'mbered-24,65l`, tiled July 24, 1900, of which the present application is a division.

The invention claimed is 1. A gas or Vapor electric lamp, having a tube containing a material or materials intended to be made incandescent by the elec-'- tric current, in combination with a non-conducting material occupying the central pori tion of the said tube. 2. A gas or vapor electric lamp, consisting of a tube containing a material or materials intended to be made incandescent by the electric current, a cooling-chamber at one end ofthe said tube, and a narrowed extension of the said chamber.

3. -A gas or vapor electric lamp, consisting of a tube containing a material or materials intended to be 'made incandescent by the electric current, a cooling-chamber at one end of the said tube, and a narrowed extension of the said chamber, one of the electrodes being located at the mouth of the narrowed eXtension.

4. A gas or vapor electric lamp, having a tube containing a material or materials intended to be made incandescent by the electric current, the said tube being surrounded by a vacuum-chamber in'which is locateda heater.

5. A gas or Vapor electric lamp, having a tube containing a materialor materials in. tended to be made incandescent by the electric current, thek said tube being surrounded by a vacuum-chamber in which is located an electrical starting-heater.

6. A gas or vaporelectric lamp, having a tube containing a material or materials intended to be made incandescent by the electric current, the said tube being surrounded by a vacuum-chamber in which kis, located a heater, the operation of which is automatically interrupted by the lighting-current.

7. A gas or vapor electric lamp, having a tube containing a material or materials intended to be` made incandescentbythe electric current, the said tube being-surrounded by a vacuum-chamber for afportionof'its length and containing an enlargement in its remaining portion.

Signed at New York, in the county of New York and-State of New York, this 15th day of December, A. D. 1900.

HENRY NOEL PoTTER.

W'itnesses:

WM.Y H. CAPEL, GILBERT E. CHAPIN. 

